On Mon, Apr 02, 2018 at 09:28:43PM +0200, Jaromír Dole?ek wrote: > The only port actually having optimization for emap is x86. Since amd64 > is also the only one supporting direct map, we are really at liberty to pick > either one.
I am not sure what you mean here - AFIK alpha and mips64 also have a direct map for all available ram set up (and some arm too, plus I guess the new aarch64 code as well). I have not seen arguments why to do it on sparc64 yet, as we can easily access all memory w/o any mapping, and a direct map has security implications. > I'd lean towards direct map, since that doesn't require > adding/removing any mapping in pmap_kernel() at all. From looking on the code, > I gather direct map is quite easy to implement for other archs like > sparc64. I'd say > significantly easier than adding the necessary emap hooks into MD pmaps. What would that hooks be? Are they documented? Martin